Known, for example, from DE 10 2005 048 602 A1 is a vane cell pump with an impeller that has a plurality of vane receptacles for receiving a radially movable pump vane. A chamber wall is formed between the adjacent vane receptacles. A part of the conveying chamber of the vane cell pump can be configured with the aid of the chamber wall. The conveying chamber is formed between a circular peripheral face of the impeller, which is interrupted by the vane receptacles, in order to form the chamber wall between the vane receptacles, the pump vanes, and a circular inner face of a housing ring disposed eccentrically with respect to the impeller.
In order that the pump vanes can abut against the inner face of the housing ring even at low rotational speeds, it is known from DE 101 42 712 A1 to expose the pump vanes to a spring force. Since the spring elements are an integral component of the impeller, however, assembly of the vane cell pump is rendered difficult since the pump vanes accommodated loosely in the vane receptacle can spring out of the vane receptacle when inserting the impeller into the housing ring. Furthermore, manufacture of the impeller is rendered difficult.
In addition, there is a continuous need to increase the pump capacity of a vane cell pump without enlarging the installation space.
In view of the foregoing, it is at least one object of the invention to provide an impeller for a vane cell pump, which is easy to manufacture and has an improved pump capacity for the same installation space. In addition, other objects, desirable features, and characteristics will become apparent from the subsequent summary or detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.
The impeller according to an embodiment of the invention for a vane cell pump comprises a plurality of vane receptacles for receiving an at least a radially movable pump vane. A chamber wall is formed between two adjacent vane receptacles to form a conveying chamber. According to an embodiment of the invention, the chamber wall has an axially projecting web with the aid of which the movement of a position ring can be delimited with respect to the radial movement of the pump vane. The position ring is made, for example, of a resilient material, which abuts radially inward against the pump vanes, to press the pump vanes radially outward. The axially projecting web can prevent the pump vanes from being pressed completely out from the vane receptacle. According to an embodiment of the invention, the chamber wall comprises a first wall region for secure receiving of the respective pump vane in the vane receptacle and a second wall region for forming a web thickness of the web for secure abutment of a sintering tool, and a third wall region for forming an enlarged conveying chamber volume.
Since the circumferential surface of the impeller has a constant radius over the entire angular range, it is possible to realize several functions simultaneously due to the shape of the chamber wall. In the area of the vane receptacles, that is, in the direction of rotation of the impeller and opposite to the direction of rotation of the impeller directly adjoining the vane receptacle, the chamber wall is configured in such a manner that the material thickness in the circumferential direction and in the radial direction is sufficient to securely receive a pump vane without there being any risk of damage to the impeller or the pump vane during operation. In the second wall region, the material thickness in particular in the radial direction is selected in such a manner that during the manufacture of the impeller by sintering, the impeller cannot be damaged by a sintering tool before the sintering. In this case, it is taken into account that if the web thickness is selected to be too thin, this can lead to damage of the web during sintering. Furthermore, use is made here of the finding that merely a partial area of the chamber wall is sufficient to be able to move the impeller in the un-sintered state with the aid of a sintering tool. This finding makes it possible for the first time to provide the third wall region, which is dimensioned to form an enlarged conveying chamber volume and to this end in particular, has a particularly small material thickness. The dimensioning of the impeller in the area of the third wall region can in particular lead to a particularly smaller web thickness or even have the result that the web is completely omitted in this region, in order to achieve a radially inwardly extending curvature of the chamber wall or of the impeller, thus increasing the conveying chamber volume. As a result, the pump capacity is increased for the same installation space. Since the increased pump capacity is not achieved by an increased speed but by an increased conveying chamber volume, the risk of cavitations is not increased but is even reduced. Since the second wall region is selected to be sufficiently large for the abutment of a sintering tool and the third wall region is not necessary for this, a dimensioning can be selected in the third wall region, which need not be selected with regard to sufficient stability during sintering. The impeller is therefore simple to produce by sintering.
The third wall region preferably has at least one radius, in particular several radii, which is smaller than the radius of the first wall region and/or smaller than the radius of the second wall region. Due to the smaller radial extension of the impeller, the volume of the conveying chamber is increased so that a large volume flow can be pumped.
In particular, it is possible that the first wall region and the second wall region have the same radius. As a result, the sintering tool can act on the still un-sintered impeller directly adjacent to the vane receptacles so that the handling of the impeller during sintering is made easier. The second wall region particularly preferably has at least one radius, which is smaller than the radius of the first wall region. It is thereby possible that the second wall region also increases the volume of the conveying chamber formed due to a reduced extension in the radial direction of the impeller. At the same time, however, the conveying chamber volume is not increased so substantially that there is a risk of damage to the un-sintered impeller due to a sintering tool.
In a preferred embodiment, the third wall region is disposed in the direction of rotation of the impeller in relation to the second wall region. This has the result that during operation of the vane cells on transition from the suction mode to the pump mode, the lowest possible inflow velocity into the conveying chamber is ensured. The risk of cavitations can thus be reduced so that a higher rotational speed of the vane cell pump is possible. This additionally increases the pump capacity. During a rotation of the impeller, the third wall region is therefore moved before the second wall region over an inlet opening or an outlet opening.
Particularly preferably for each chamber wall precisely one second wall region and precisely one third wall region are provided between precisely two first wall regions. This allows a more regular configuration of the impeller. Furthermore, it is possible to configure the second wall region to be comparatively wide so that if the sintering tools are positioned inaccurately, the sintering tool comes to rest securely in the second wall region.
The second wall region and the third wall region preferably go over continuously into one another. This results in a uniform configuration of the chamber wall so that fluidically unfavorable flows such as, for example, turbulence at sudden changes in flow cross section can be avoided. The pump capacity is thus improved.
In particular, the web has a constant inside radius. This results in an impeller configuration which is easy to produce. Furthermore, the impeller can easily be mounted by inserting the impeller with the accommodated pump vanes into the housing ring and only then inserting the position ring. To this end, this position ring, which is in particular made of a flexible material, can initially be supported on the inner face of the web before the position ring is successively applied to the radially inner face of the respective pump vane. This facilitates assembly.
The embodiments of the invention further relate to a vane cell pump with the aid of which in particular engine oil of an automobile can be conveyed. The vane cell pump comprises a housing ring in which an impeller is preferably disposed eccentrically. The impeller can be configured and further developed as described previously. The vane receptacles of the impeller accommodate pump vanes against which a resilient position ring abuts radially inwardly. In each case, one conveying chamber is formed between the housing ring, the respective chamber wall, and the pump vanes assigned to the respective chamber wall. This vane cell pump has an increased pump capacity in relation to its installation space and can easily be produced.
It is particularly preferable if the housing ring which can be a part of the housing of the vane cell pump, is pivotally mounted under pretension in a plane of the impeller relatively movable to the impeller. As a result, it is possible for the impeller to abut against the housing ring in at least one position without the rotation of the impeller being hereby impaired. Due to the pivotability of the housing ring relative to the impeller, it is thus possible to achieve the largest possible different in the pump chamber volume.